Electrical connector



Feb. 4, 1969 KolcHl TAKr-:UcHl ETAL 3,426,310

ELECTRICAL CONNECTOR Filed April 26, 1967 r IIIIIII United States Patent C U.s. ycl. 339-17 z claims 1m. cl. Hosr 25/00; Hosk 1/00 ABSTRACT F THE DISCLOSURE An electrical contact piece is made by tortuously bending a resilient continuous electric conductor of circular cross-section into a letter W configuration having a pair of adjacent coplanar contact portions each including an inner conductor and an outer conductor which are formed by folding back said continuous conductor. A gap smaller than the diameter of the conductor is formed between said contact portions. One contact piece acting as a plug and the other acting as a receptacle are mounted at right angles with respect to each other and to be movable relatively so that said contact pieces are intertted at said gaps to form a criss-cross.

This invention relates to improvements of an electrical connector, more particularly to an electrical connector adapted to removably connect input and output circuits of printed circuit boards utilized in electric computers or the like electric apparatus.

In one form of a contact piece utilized in a plug and a receptacle comprising a connecting means utilized in electric computers and the like, one end of a resilient metal sheet is punched to form a longitudinal slot. In assembling the electrical connector two such sheets are combined at right angles with one of the sheets received in the slot of the other. However in order to smoothly interfit such contact pieces punched out of metal sheets it is necessary to taper the contact surfaces. Thus, it is not only ditiicult to manufacture these contact pieces at high accuracy but their cost of manufacturing is expensive. Moreover as the contact pieces are made of sheet stocks, their contact pressure is weak thus resulting in inaccurate contact.

It is the object of this invention to provide an improved electrical connector without accompanying the above described defects.

In accordance with this invention, the contact piece is made of an elastic electroconductive round rod or wire. The contact piece according to this invention can be readily manufactured by bending a round rod in the desired configuration and then plating with gold. Moreover as the resiliency of the contact piece is large, electrical connection can be positively made with minimum contact resistance.

The invention can be more fully understood from the following description taken in connection with the accompanying drawings, in which;

FIG. l shows a perspective View of electric connectors embodying this invention as applied to an electric computer;

FIG. 2 is a plan view of the assembly shown in FIG. 1 taken along a line II-II; and

FIGS. 3 and 4 show contact pieces of this invention utilized as a plug and a receptacle.

Referring now to the accompanying drawings which illustrate electric connectors embodying this invention as applied for connecting the main body of an electric corn- ICE putor and printed circuit boards as shown in FIGS. 1 and 2, the electric computer `1 comprises a main body 2 (only a portion thereof is shown) and a plurality of printed circuit boards 3 removably associated therewith. Each of these printed circuit boards 3 is provided with a contact place 5 at one end 4 facing to the main body 2, said contact piece 5 serving as a connecting plug 6. A pair of spaced parallel guide rails 7 is provided for the main body 2 to guide the printed circuit boards 3 when they are inserted or removed and to hold them in predetermined positions. Although not shown in the drawing, an identical pair of guide rails is provided on the lower edge of the main body. The main body is also provided with a base plate 9 having contact pieces 8 at positions corresponding to contact plugs 6 on respective printed circuit boards 3 and close to guide rails 7, said contact pieces 8 acting as receptacles 10 to cooperate with plugs 6. The reference numeral 11 illustrates one of the circuit components associated with each printed circuit board 3. It is to be understood that a plurality of contact pieces 5 are provided along the edge 4 and that corresponding number of contact pieces are secured to the base plate 9 of the main body 2 to co-operate therewith.

The detail of contact pieces 5 and `8 acting as a plug 6 and a receptacle 10 will now be described by referring to FIGS. 3 and 4. As shown in FIG. 3 the contact piece 5 is formed by tortuously bending a resilient round rod or wire of an electric conductor into a letter W configuration with adjacent legs 12 and 13, and 14 and 15 nearly in contact, and with inner legs 13 and 14 spaced apart by a distance slightly smaller than the diameter of the rod to form a pair of coplanar contact portions 16. Free ends of the outside legs 12 and 15 are bent in the same direction to form mounting portions `19. Similarly, the contact piece 8 as shown in FIG, 4, is also formed in a letter W configuration with a pair of contact portions lr6. However the free ends 17 and 18 are made straight to form mounting portions 20.

As shown in FIG. 2, the plug 6 is formed by securing a contact piece 5 to the end 4 of the printed circuit board 3. The manner of securing the contact piece Iwill be described in connection with the printed circuit board comprising the lower line A in FIG. 2.

The printed circuit board 3 illustrated is of the type in which one side is printed and the other side is formed with strips of copper foil. At the end 4 of the printed circuit board 3 are provided perforations 22 to receive mounting portion 19 of the contact piece 5. In each of these perforations 22, an eyelet 23 is secured to receive one end of the mounting portion. On one side of the printed circuit board 3, the ends |17 and 18 of the mounting portion 19 and eyelets 22 are soldered to the conductor 21 as at 24. Similarly on the other side of the board 3 the ends 17 and 18 are respectively soldered to respective eyelets 22 as at 24a.

Each receptacle 10 is lformed by securing the contact piece 8 at a proper position of the base plate 9 in a manner identical to that of the plug 6. As can be noted from the accompanying drawings each pair of Contact pieces 5 and 8 comprisingk the plug 6 and the receptacle 10 are mounted at right angles on the printed circuit board 3 and the base plate 9 respectively. The plugs 6 are connected to various components 11 and to electric circuits including the strip 21, whereas the receptacles 10 are connected to various circuits contained in the main body 2 via conductor leads 25 soldered to the ends 17 and 18 of the contact pieces 8.

In order to mutually engage the plug 6 and the receptacle 10 constructed as described above, printed circuit lboard 3 which is held in the disengaged state as shown by the line A in FIGS. 1 and 2 is slided along the guide rails 7 forwards the main body 2.

As shown in the drawing since the tips of the contact portions 16 of respective contact pieces 5 and 8 are rounded, these contact pieces can intert very smoothly against the spring pressure provided by folded back legs which acts to reduce the gap between contact portions 16. Thus, each contact piece serves to guide the insertion of the other thus insuring rm contact between two contacts. Engagement between two contacts will be completed when the inner edge of the printed circuit board 3 comes to contact with the base plate 9 of the main body Z. This intertting condition is shown by the elements on the line B in Which contacts are made at four points or along sfour lines on the surface of respective inner conductors comprising contact portions.

The magnitude of the contact pressure @and the sliding action between contact portions 16 are made suitable by preliminarily adjusting the gap between inner conductors 13 and 14 of the contact pieces 5 and 8 at the time of shaping. Further the contact resistance can be suitably reduced by plating the round rod with gold.

The electric connector of this invention has following advantages.

(1) As the contact piece is made of a rod or wire of circular cross-section and formed into a letter W configuration intertted contact pieces contact each other at symmetrical four points or lines whereby to provide lar-ge contact -area with small contact resistance which assures positive contact regardless of accidential force acting upon the mounting portion.

(2) Cross-section of circular configuration assures high resiliency, positive connection and good contact.

(3) This configuration also assures Isimple working, and less cost of working and material.

(4) Utilization of a rod or wire of circular cross-section requires minimum surface area and hence minimum quantity of gold required for plating the Contact piece to improve its contact.

(5) By utilizing a thin wire the space lfactor of the contact piece can be reduced.

(6) As each contact portion of the contact piece comprises folded back conductor, the mechanical strength can be increased.

Although in the illustrated example the novel connectors have -been shown as applied to interconnect the main body of an electric conductor and printed circuit boards, it will be clear that the novel connectors can equally be used to constitute plugs and receptacles for any other electric devices and components by merely modifying their mounting portions.

Thus, according to this invention there are provided electrical connectors imade of an electrical conductor rod or wire of circular cross-section which can be made very easily and have smlall contact resistance. Moreover, a particular configuration of the contact piece assures ready and accurate connection.

While the invention has been described in terms of a preferred embodiment thereof it will -be obvious to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In an electrical connector including cooperating plug and a receptacle each having a contact piece, the improvement which comprises a contact piece made of a resilient electric conductor of circular cross-section tortuously bent into a letter W conguration, said contact piece having a pair -of adjacent coplanar contact portions each including an inner conductor and an outer conductor which are formed by `folding back a continuous conductor, said adjacent contact portions being spaced by a gap which is a little smaller than the diameter of said electric conductor, the outer end `of the outer conductor forming a mounting portion, and the contact piece constituting said plug and the contact piece constituting said receptacle being mounted at right angles with respect to each other and to be movable relatively so that said contact pieces intert at said gaps.

2. The electrical connector according to claim 1 wherein one of said cooperating contact pieces is secured to an electric apparatus such las an electric computer and the other contact piece is mounted upon a printed circuit board guided to move toward and away from said electric apparatus.

References Cited UNITED STATES PATENTS 2,994,05 6 7/ 1961 FOX.

3,149,894 9/1964 Fox.

3,157,452. 11/ 1964 Dorjee et al.

FOREIGN PATENTS 2,068,598 9/1898` Great Britain.

1,408,382 7 1965 France.

RICHARD E. MOORE, Primary Examiner.

PATRICK A. CLTFF ORD, Assistant Examiner.

U.S. Cl. X.R. 

